[Skeletal muscle reaction in man to a decrease in gravitation].
Functional characteristics the triceps surae muscle were studied in sex subjects exposed for 7 days to decreased unweighting induced by "dry" immersion (DI). After DI, the maximal voluntary contraction was a significant reduced by 33.8%, and the electrically evoked tetanic contraction (Po), and the twitch tension (Pt) was not significantly changed (8.2 and 9.9%, respectively). The force deficiency increased by 44.1% (P < 0.01). The twitch time-to-peak did not change, and to half-relaxation decreased by 5.3%. The Pt:Po ratio was decreased by 8.7% (P < 0.01) after "dry" immersion. The muscle surface action potential increased by 18.8% (P < 0.01), and a decrease of the amplitude and the area by 14.6% (P < 0.05), and 2.8% (P < 0.01), respectively. A comparison of the electrical and mechanical alterations recorded in the muscle suggests that due to decreased functional demands there may be an alteration not only in peripheral processes associated with the contraction, but also in the central (motor) command to the acting apparatus. We suppose that among peripheral sites, intracellular processes of contraction play the major in the contractile impairment recorded during "dry" immersion.
Koriak
Iu A
IuA
D000200:Action Potentials / Q000502:physiology; D000293:Adolescent; D000328:Adult; D004576:Electromyography / Q000295:instrumentation / Q000379:methods / Q000706:statistics & numerical data; D006801:Humans; D018472:Hypogravity; D007101:Immersion / Q000503:physiopathology; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D018709:Statistics, Nonparametric; D013997:Time Factors
Reaktsiia skeletnoĭ myshtsy u cheloveka na snizhenie gravitatsii.